CN205714857U - A kind of antecurvature multiple wing type centrifugal blower fan - Google Patents

Abstract

The utility model discloses a forward-curved multi-blade centrifugal fan, which comprises a volute and an impeller; the volute comprises a volute, and sequentially tangent and smoothly connected first curved surface, second curved surface and third curved surface. Surface; the eccentric arrangement of the impeller and the volute is used to increase the diameter of the impeller. In the utility model, the eccentric installation of the impeller relative to the volute increases the diameter of the impeller, significantly improves parameters such as air volume and pressure, reduces noise, prevents fan surge, and improves the performance of the fan; The volute shape line is improved, the space volume is saved, the structure is simple, there is no welding process, the processing cost is low, and the volute manufacturing is more convenient.

Description

A forward curved multi-blade centrifugal fan

technical field

The utility model relates to the field of air conditioning and ventilation, in particular to a forward-curved multi-blade centrifugal fan, which is especially suitable for a small forward-curved multi-blade double-suction centrifugal fan.

Background technique

The multi-blade centrifugal fan has the advantages of large flow coefficient, high pressure coefficient, small size coefficient and relatively low noise, and is widely used in the air-conditioning industry. The forward curved multi-blade centrifugal fan is a kind of centrifugal fan and belongs to the blade fan. The main feature of this fan impeller is the use of forward curved blades with a large wheel diameter ratio (0.8~0.95), relatively large width (about 0.4 times the outer diameter of the impeller), and a large number of blades (32~64). The air inlet of the volute is fitted with the impeller in a gap type, and the axial gap value is generally 0.02~0.025 times the outer diameter of the impeller. In the multi-blade centrifugal fan, a built-in motor is usually used, which is located in the center area of the impeller to save space.

The special structure of the multi-blade centrifugal fan makes its working characteristics different from other forms of fans. Its work efficiency is relatively low, which limits its scope of use to a certain extent. In order to improve the efficiency of the multi-blade centrifugal fan, the traditional equal-thickness single-arc straight blades are changed into airfoil blades, trapezoidal blades or twisted blades, but it is not easy to determine a reasonable optimization scheme, and it causes complex structures, difficult processing, The cost is too high and the practical value is not large.

The volute design of the multi-blade centrifugal fan for air conditioning cannot fully refer to the design methods and empirical data of industrial fans. The coincidence of the geometric center of the impeller and the volute may not be the best installation position, and the traditional volute profile may not be the most reasonable. However, the two-dimensional design theory of the inner wall of the volute and the variable helix angle design theory proposed by some researchers based on this are too complicated and poor in operability.

Therefore, the prior art still needs to be improved and developed.

Utility model content

In view of the above deficiencies in the prior art, the purpose of this utility model is to provide a forward curved multi-blade centrifugal fan, the impeller and volute are arranged eccentrically, the diameter of the impeller is increased, and the volute is formed by three sections of arc surface to simplify the mechanism of the centrifugal fan .

The technical scheme of the utility model is as follows:

A forward curved multi-blade centrifugal fan, including a volute and an impeller;

The volute includes a volute tongue, and a first curved surface, a second curved surface and a third curved surface which are sequentially tangent and smoothly connected;

The eccentric arrangement of the impeller and the volute is used to increase the diameter D′ of the impeller.

Further, in the forward curved multi-blade centrifugal fan, the diameter of the impeller arranged concentrically with the volute is D, and the diameter of the impeller arranged eccentrically is D´=1.1D.

Further, in the forward curved multi-blade centrifugal fan, the eccentric value of the impeller and the volute is L=(D´-D)/2.

Further, in the forward curved multi-blade centrifugal fan, the wheel diameter ratio of the impeller is 0.85, and the relative width of the impeller is 0.75D.

Further, in the forward curved multi-blade centrifugal fan, the number of blades of the impeller is 48.

The forward curved multi-blade centrifugal fan provided by the utility model installs the impeller eccentrically relative to the volute to increase the diameter of the impeller. The power of the centrifugal fan increases with the increase of the flow rate and can be overloaded. The parameters such as air volume and pressure are significantly improved, and the noise is reduced. , there will be no fan surge, and the performance of the fan is improved; at the same time, the three-section arc surface is used to form the volute to simplify the volute profile, save space and volume, the structure is simple, there is no welding process, and the processing cost is low, making the volute manufacturing more convenient. convenient.

Description of drawings

Figure 1 is a schematic structural diagram of a traditional non-eccentric centrifugal fan.

Fig. 2 is a schematic diagram of a traditional four-segment arc volute structure.

Fig. 3 is a structural schematic diagram of a forward-curved multi-blade centrifugal fan of the present invention.

Fig. 4 is a structural schematic diagram of the impeller in the forward curved multi-blade centrifugal fan of the present invention.

Fig. 5 is an effect diagram of the fan flow field distribution of the forward curved multi-blade centrifugal fan of the present invention.

Fig. 6 is a measured performance curve of the forward-curved multi-blade centrifugal fan of the present invention.

detailed description

The utility model provides a forward-curved multi-blade centrifugal fan. In order to make the purpose, technical solution and effect of the utility model clearer and clearer, the utility model will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

As shown in Figure 1, Figure 1 is a schematic structural diagram of a traditional non-eccentric centrifugal fan. The function of the volute 1 of the centrifugal fan is to concentrate and guide the gas leaving the impeller 2, and to convert part of the kinetic energy of the gas into static pressure. . If the profile of the inner wall of the volute 1 is improperly designed, the kinetic energy loss and noise will increase, especially when the centrifugal fan deviates from the design working condition, and the diameter of the impeller 2 is D. The rotation center of the impeller 2 of the traditional conventional centrifugal fan is consistent with the base square center of the volute 1, that is, they are installed concentrically, and their geometric centers coincide. The type 1 line of the volute of a traditional conventional centrifugal fan is approximated by four arcs, usually an equilateral base square or a unequal base square. As shown in Figure 2, the radii of the four arcs are R1', R2', R3' and R4' respectively. The design concept of the utility model is based on the premise of ensuring that the performance of the fan is not reduced, optimizing the structure of the fan, and simplifying the volute 1-shaped line. That is to say, the profile of the inner wall of the volute 1 is reduced from the traditional four-section arc surface to three tangent arc surfaces, the size of the volute 1 is not much different, the structure is relatively simple, and the manufacture is more convenient.

Please refer to Fig. 3, the forward curved multi-blade centrifugal fan provided by the utility model includes a volute 1 and an impeller 2; compared with the prior art, the diameter of the impeller 2 is increased to D', the utility model described The volute 1 comprises a first curved surface 3 (with a radius R1), a second curved surface 4 (with a radius R2) and a third curved surface 5 (with a radius R3) and a volute tongue, the first curved surface 3 , The surfaces of the second curved surface 4 and the third curved surface 5 are sequentially tangent and smoothly connected, and the three-section arc surface is used to form the volute 1, which simplifies the shape line of the volute 1, and simplifies the traditional four-section arc approximate molding volute 1 , so that the manufacture of the volute 1 is more convenient, and the parts are manufactured by moulding, which has the advantages of no welding process, convenient manufacture and low processing cost.

Please refer to Fig. 2, Fig. 2 is a schematic diagram of the structure of the volute 1 of the traditional four-segment arc. The volute 1 type line of the traditional conventional centrifugal fan is approximated by four arcs, which is usually an equilateral base square or a scalene base. square. The impeller 2 is the part of the fan that is finally in contact with the gas medium and does work on it. The main structural parameters of the fan impeller include the outer diameter of the impeller, the width of the impeller, the ratio of inner and outer wheel diameters, the installation angle of the blade inlet and outlet, the number of blades, etc. Fan performance is affected.

According to the law of fan similarity, the air volume has a cubic relationship with the diameter of the impeller, and the wind pressure has a quadratic relationship with the diameter of the impeller. It can be seen that the diameter of the impeller has a great influence on the performance of the fan. However, due to some actual needs, the size of the fan is limited and cannot be enlarged. If the performance of the fan is not satisfactory, if the diameter of the impeller is increased, the size of the volute cannot be enlarged simultaneously, that is, it is not advisable to use the same series of large-scale fans. If the diameter of the impeller is directly enlarged, the volute tongue clearance will be too small, the efficiency will decrease, and the noise will increase. Because the internal space of the volute is limited, the above scheme cannot be implemented.

As shown in Figure 3, the technical solution for increasing the diameter of the impeller proposed by the utility model based on the above-mentioned technical problems is: the impeller 2 and the volute 1 in the centrifugal fan are arranged eccentrically, so that the diameter of the impeller 2 is D ´ Increased. In the utility model, the installation position of the impeller 2 and the volute 1 has a certain eccentricity, which ensures the external dimensions and the volute tongue clearance of the centrifugal fan; that is, the impeller 2 is offset to the inner side of the volute 1 to increase the diameter of the impeller 2, and the diameter of the impeller 2 The increase can significantly improve performance parameters such as air volume and pressure, improve the efficiency of the fan, reduce the noise level, and improve the performance of the fan.

Specifically, as shown in Figure 1 and Figure 3, when the impeller 2 of the traditional centrifugal fan is concentrically arranged with the volute 1, the diameter of the impeller 2 is D. The diameter of the impeller 2 D´=1.1D; the eccentric value of the impeller 2 and the volute 1 L=(D´-D)/2. The overall size of the centrifugal fan can be kept unchanged, and the form of the blade does not need to be modified, so the performance of the centrifugal fan can be improved.

Further, as an embodiment of the present invention, as shown in Fig. 3 and Fig. 4, the present invention sets the wheel diameter ratio of the impeller 2 to 0.85, sets the relative width of the impeller 2 to 0.75D, and the The number of blades of the impeller 2 is 48. The centrifugal fan with the above technical features can significantly improve performance parameters such as air volume and pressure, improve the efficiency of the centrifugal fan, and reduce the noise level of the centrifugal fan.

The blades of the impeller 2 are set as single-arc straight blades of equal thickness, so that the blades are in the shape of blades.

Please refer to Fig. 5 and Fig. 6, Fig. 5 is an effect diagram of the fan flow field distribution of the forward curved multi-blade centrifugal fan of the present invention. In the figure, the air flow enters the centrifugal fan from the air inlets on both sides of the centrifugal fan, passes through the high-speed rotation of the impeller 2, does work on it, and is transported to the designated working area by the air outlet, so that the internal fluid flow of the fan can be intuitively recognized, and the fluid density is high. And the flow efficiency is very high. Fig. 6 is a measured performance curve of the forward-curved multi-blade centrifugal fan of the present invention. The four curves in the figure are from top to bottom: efficiency-flow curve, power-flow curve, total pressure-flow curve and static pressure-flow curve. It can be seen that the maximum static pressure efficiency of the centrifugal fan of the utility model reaches 30%, and it is relatively good in the field of forward-bending multi-wings and the built-in motor; the power increases with the increase of the flow rate, and it can be overloaded; It is not obvious, and there will be no fan surge; the noise level is reduced while the performance parameters such as air volume and pressure are significantly improved, and the performance of the fan is improved.

To sum up, the forward curved multi-blade centrifugal fan provided by the utility model installs the impeller eccentrically relative to the volute to increase the diameter of the impeller, and the power of the centrifugal fan increases with the increase of the flow rate so that it can be overloaded, and the air volume and pressure can be significantly improved. parameters, reducing noise, no fan surge, and improved fan performance; at the same time, the three-section arc surface is used to form the volute to simplify the volute profile, save space and volume, simple structure, no welding process, low processing cost, Make the volute manufacturing more convenient.

It should be understood that the application of the present utility model is not limited to the above examples, and those of ordinary skill in the art can improve or change according to the above description, for example, all these improvements and changes should belong to the appended claims of the present utility model scope of protection.

Claims (5)

1. A forward curved multi-blade centrifugal fan is characterized in that it comprises a volute and an impeller; The volute includes a volute tongue, and a first curved surface, a second curved surface and a third curved surface which are sequentially tangent and smoothly connected; The impeller is arranged eccentrically with the volute, and the diameter of the impeller after the eccentric arrangement is larger than that of the impeller arranged concentrically. 2. The forward-curved multi-blade centrifugal fan according to claim 1, wherein the diameter of the impeller arranged concentrically with the volute is D, and the diameter of the impeller arranged eccentrically is D´=1.1D. 3. The forward-curved multi-blade centrifugal fan according to claim 2, wherein the eccentric value of the impeller and the volute is L=(D´-D)/2. 4 . The forward curved multi-blade centrifugal fan according to claim 3 , wherein the wheel diameter ratio of the impeller is 0.85, and the relative width of the impeller is 0.75D. 5 . The forward-curved multi-blade centrifugal fan according to claim 4 , wherein the number of blades of the impeller is 48. 6 .